Estimation of Heterosis and General And Specific Combining Abilities in Some Sunflower (Helianthus Annuus L.) Hybrids

Estimation of Heterosis and General And Specific Combining Abilities in Some Sunflower (Helianthus Annuus L.) Hybrids

Author:

Bushara, Mohamed Ahmed Mohamed

Abstract:

Twenty-eight sunflower hybrids were produced, using two cytoplasmically
male sterile lines as female parents and fourteen fertility restorer lines (testers).
The hybrids and a commercial check (Hysun-33) were evaluated for two seasons
(2000/01and 2001/02) at two locations; namely, the University of Khartoum Farm
at Shambat and Rahad Research Station . The experiment was carried out under
irrigation, using a randomized complete block design with three replications.
Significant differences were detected among the tested hybrids for most of
the studied characters, at the two locations and for the two seasons. Moreover, a
wide range of variability among the fourteen testers and between the two lines was
obtained for most of the characters. The genotype x location interaction was
significant for number of seeds per head, 1000-seed weight and seed yield per
head. In addition, significant location x season, genotype x season and genotype x
location x season interactions were detected for all characters.
Negative heterotic values, under the better- parent, were expressed by some
of the hybrids produced from the female parents Kr and Ka for plant height, days
to 50% flowering, days to maturity and percentage of empty seeds per head over
the four environments. Positive heterosis over the better-parent was expressed by
all the hybrids for stem diameter, head diameter, number of seeds per head, 1000-
seed weight, seed yield per head and seed yield per hectare over the four
environments.
At Shambat, 14.3% and 78.6% of the hybrids obtained from the female
parent Kr were high yielders than the commercial check in the first and the second
seasons, respectively, wheras all the hybrids from the female Ka were high
yielders than the check in the second season. At Rahad, 21.4% of Ka hybrids were
high yielders than the check in the first season.
All the characters studied were controlled by additive gene action over the
four environments, except seed yield per head and seed yield per hectare at
Shambat in the first season and head diameter and 1000-seed weight at Rahad in
the first season, which were controlled by non-additive gene action.
At Shambat, the best general combiner males for seed yield and seed
components were SH-24 and SH-10 for number of seeds per head, SH-5 and SH-
24 for percentage of empty seeds, SH-6 and SH-2 for 1000-seed weight, SH-23
and SH-12 for seed yield per head and SH-23 and SH-2 for seed yield per hectare
respectively, in the first and the second seasons. At Rahad, the best general
combiner males were SH-12 and SH-8 for number of seeds per head , SH-3 and
SH-21 for 1000-seed weight, SH-6 and SH-7 for seed yield per head and seed
yield per hectare respectively, in the first and the second seasons. With regard to
the females, Ka was the better general combiner for all the characters studied over
the environments, except 1000-seed weight at Rahad in both seasons, where the
female Kr was the better general combiner.
The highest specific combining ability (SCA) estimates at Shambat were
scored by the hybrids SHR-2 and SHR-13 for number of seeds per head, SHR-5
and SHR-13, for percentage of empty seeds, SHA-18 and SHA-24 for 1000-seed
weight, SHA-6 and SHR-2 for seed yield per head and seed yield per hectare,
respectively, in the first and the second seasons. At Rahad, the highest SCA
estimates were obtained for SHR-2 and SHR-9 for number of seeds per head,
SHA-18 and SHA-24 for 1000-seed weight and SHR-9 and SHA-6 for seed yield
per head and seed yield per hectare in the first and the second seasons,
respectively.
The analysis of stability parameters indicated that the hybrids produced
from the female parent Ka as well as the check were the highest yielders but
sensitive to changing environments, hence they were adapted to favourable
environments, on the other hand, those produced from the female parent Kr were
resistant to changing environments, but they were average yielders, and thus they
were adapted to poor environments.